Equation Of State

Information about Equation Of State

For the use of this concept in cosmology, see Equation of state (cosmology)

In physics and thermodynamics, an equation of state is a relation between state variables.<ref name="Perrot" >Perrot, Pierre (1998). A to Z of Thermodynamics. Oxford University Press. ISBN 0-19-856552-6. More specifically, an equation of state is a thermodynamic equation describing the state of matter under a given set of physical conditions. It is a constitutive equation which provides a mathematical relationship between two or more state functions associated with the matter, such as its temperature, pressure, volume, or internal energy. Equations of state are useful in describing the properties of fluids, mixtures of fluids, solids, and even the interior of stars.

Overview

The most prominent use of an equation of state is to predict the state of gases and liquids. One of the simplest equations of state for this purpose is the ideal gas law, which is roughly accurate for gases at low pressures and high temperatures. However, this equation becomes increasingly inaccurate at higher pressures and lower temperatures, and fails to predict condensation from a gas to a liquid. Therefore, a number of much more accurate equations of state have been developed for gases and liquids. At present, there is no single equation of state that accurately predicts the properties of all substances under all conditions.

In addition to predicting the behavior of gases and liquids, there are also equations of state for predicting the volume of solids, including the transition of solids from one crystalline state to another. There are equations that model the interior of stars, including neutron stars. A related concept is the perfect fluid equation of state used in cosmology.

Historical

Boyle's law (1662)

Boyle's Law was perhaps the first expression of an equation of state. In 1662 Robert Boyle, an Irishman, performed a series of experiments employing a J-shaped glass tube, which was sealed on one end. Mercury was added to the tube, trapping a fixed quantity of air in the short, sealed end of the tube. Then the volume of gas was carefully measured as additional mercury was added to the tube. The pressure of the gas could be determined by the difference between the mercury level in the short end of the tube and that in the long, open end. Through these experiments, Boyle noted that the gas volume varied inversely with the pressure. In mathematical form, this can be stated as:

PV = constant

The above relationship has also been attributed to Edme Mariotte and is sometimes referred to as Mariotte's law. However, Mariotte's work was not published until 1676.

Charles's law or Law of Charles and Gay-Lussac (1787)

In 1787 the French physicist Jacques Charles found that oxygen, nitrogen, hydrogen, carbon dioxide, and air expand to the same extent over the same 80 kelvin interval. Later, in 1802, Joseph Louis Gay-Lussac published results of similar experiments, indicating a linear relationship between volume and temperature:

V₁/T₁ = V₂/T₂

Dalton's law of partial pressures (1801)

Dalton's Law of Partial Pressure: The pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone.

Mathematically, this can be represented for n species as:

Pressure_total = Pressure₁ + Pressure₂ + ... + Pressure_n

The ideal gas law (1834)

In 1834 Émile Clapeyron combined Boyle's Law and Charles' law into the first statement of the ideal gas law. Initially the law was formulated as PV_m=R(T_C+267) (with temperature expressed in degrees Celsius). However, later work revealed that the number should actually be closer to 273.2, and then the Celsius scale was defined with 0 °C = 273.15 K, giving:

PV_m=R(T_C+273.15)

van der Waals equation of state

In 1873, J. D. van der Waals introduced the first equation of state derived by the assumption of a finite volume occupied by the constituent molecules.<ref name="van der Waals" >van der Waals, J. D. (1873). On the Continuity of the Gaseous and Liquid States (doctoral dissertation). Universiteit Leiden. His new formula revolutionized the study of equations of state, and was most famously continued via the Redlich-Kwong equation of state and the Soave modification of Redlich-Kwong.

Major Equations of State

In the following equations the variables are defined as follows. Any consistent set of units may be used, although SI units are preferred. Absolute temperature refers to use of the Kelvin (K) or Rankine (°R) temperature scales, with zero being absolute zero.

P = pressure

V = volume

n = number of moles of a substance

V_m = V/n = molar volume, the volume of 1 mole of gas or liquid

T = absolute temperature

R = ideal gas constant (8.314472 J/(mol·K))

P_c = pressure at the critical point

V_c = molar volume at the critical point

T_c = absolute temperature at the critical point

Classical ideal gas law

The classical ideal gas law may be written:

$\text{[math]}$

The ideal gas law may also be expressed as follows

$\text{[math]}$

where $\text{[math]}$ is the density, $\text{[math]}$ is the adiabatic index (ratio of specific heats), $\text{[math]}$ is the internal energy per unit mass (the "specific internal energy"), $\text{[math]}$ is the specific heat at constant volume, and $\text{[math]}$ is the specific heat at constant pressure.

Cubic Equations of State

van der Waals equation of state

The Van der Waals equation of state may be written:

$\text{[math]}$ , note that $\text{[math]}$ is molar volume.

Where $\text{[math]}$ and $\text{[math]}$ are constants that depend on the specific material. They can be calculated from the critical properties as:

$\text{[math]}$

Also written as

$\text{[math]}$

Proposed in 1873, the van der Waals equation of state was one of the first to perform markedly better than the ideal gas law. In this landmark equation $\text{[math]}$ is called the attraction parameter and $\text{[math]}$ the repulsion parameter or the effective molecular volume. While the equation is definitely superior to the ideal gas law and does predict the formation of a liquid phase, the agreement with experimental data is limited for conditions where the liquid forms. While the van der Waals equation is commonly referenced in text-books and papers for historical reasons, it is now obsolete. Other modern equations of only slightly greater complexity are much more accurate.

The van der Waals equation may be considered as the ideal gas law, “improved” due to two independent reasons:

Molecules are thought as particles with volume, not material points. Thus $\text{[math]}$ cannot be too little, less than some constant. So we get ( $\text{[math]}$ ) instead of $\text{[math]}$ .
While ideal gas molecules do not interact, we consider molecules attracting others within a distance of several molecules' radii. It makes no effect inside the material, but surface molecules are attracted into the material from the surface. We see this as diminishing of pressure on the outer shell (which is used in the ideal gas law), so we write ( $\text{[math]}$ something) instead of $\text{[math]}$ . To evaluate this ‘something’, let's examine an additional force acting on an element of gas surface. While the force acting on each surface molecule is ~ $\text{[math]}$ , the force acting on the whole element is ~ $\text{[math]}$ ~ $\text{[math]}$ .

Redlich-Kwong equation of state

$\text{[math]}$

Introduced in 1949 the Redlich-Kwong equation of state was a considerable improvement over other equations of the time. It is still of interest primarily due to its relatively simple form. While superior to the van der Waals equation of state, it performs poorly with respect to the liquid phase and thus cannot be used for accurately calculating vapor-liquid equilibria. However, it can be used in conjunction with separate liquid-phase correlations for this purpose.

The Redlich-Kwong equation is adequate for calculation of gas phase properties when the ratio of the pressure to the critical pressure (reduced pressure) is less than about one-half of the ratio of the temperature to the critical temperature (reduced temperature):

$\text{[math]}$

Soave modification of Redlich-Kwong

$\text{[math]}$

Where ω is the acentric factor for the species.

for hydrogen:

$\text{[math]}$

In 1972 Soave replaced the a/√(T) term of the Redlich-Kwong equation with a function α(T,ω) involving the temperature and the acentric factor. The α function was devised to fit the vapor pressure data of hydrocarbons and the equation does fairly well for these materials.

Note especially that this replacement changes the definition of a slightly, as the $\text{[math]}$ is now to the second power.

Peng-Robinson equation of state

$\text{[math]}$

where, $\text{[math]}$ is the acentric factor of the species and $\text{[math]}$ is the universal gas constant.

The Peng-Robinson equation was developed in 1976 in order to satisfy the following goals:^[1]

The parameters should be expressible in terms of the critical properties and the acentric factor.
The model should provide reasonable accuracy near the critical point, particularly for calculations of the Compressibility factor and liquid density.
The mixing rules should not employ more than a single binary interaction parameter, which should be independent of temperature pressure and composition.
The equation should be applicable to all calculations of all fluid properties in natural gas processes.

For the most part the Peng-Robinson equation exhibits performance similar to the Soave equation, although it is generally superior in predicting the liquid densities of many materials, especially nonpolar ones. The departure functions of the Peng-Robinson equation are given on a separate article.

Elliott, Suresh, Donohue equation of state

The Elliott, Suresh, and Donohue (ESD) equation of state was proposed in 1990. The equation seeks to correct a shortcoming in the Peng-Robinson EOS in that there was an inaccuracy in the van der Waals repulsive term. The EOS accounts for the effect of the shape of a non-polar molecule and can be extended to polymers with the addition of an extra term (not shown). The EOS itself was developed through modeling computer simulations and should capture the essential physics of the size, shape, and hydrogen bonding.

$\text{[math]}$

Where:

$\text{[math]}$ a “shape factor?

$\text{[math]}$

Non-cubic Equations of State

Dieterici equation of state

$\text{[math]}$

Where a is associated with the interaction between molecules and b takes into account the finite size of the molecules, similarly to the Van der Waals equation.

The reduced coordinates are:

$\text{[math]}$

Virial Equations of State

Virial equation of state

$\text{[math]}$

Although usually not the most convenient equation of state, the virial equation is important because it can be derived directly from statistical mechanics. If appropriate assumptions are made about the mathematical form of intermolecular forces, theoretical expressions can be developed for each of the coefficients. In this case B corresponds to interactions between pairs of molecules, C to triplets, and so on. Accuracy can be increased indefinitely by considering higher order terms.

It can also be used to work out the Boyle Temperature (the temperature at which B = 0 and ideal gas laws apply) from a and b from the Van der Waals equation of state. If you use the value for B shown below;

$\text{[math]}$

The BWRS equation of state

Main article: Benedict-Webb-Rubin

$\text{[math]}$

ρ = the molar density

Values of the various parameters for 15 substances can be found in:

K.E. Starling, Fluid Properties for Light Petroleum Systems. Gulf Publishing Company (1973).

Other Equations of State of Interest

Stiffened equation of state

When considering water under very high pressures (typical applications are underwater nuclear explosions, sonic shock lithotripsy, and sonoluminescence) the stiffened equation of state is often used:

$\text{[math]}$

where $\text{[math]}$ is the internal energy per unit mass, $\text{[math]}$ is an empirically determined constant typically taken to be about 6.1, and $\text{[math]}$ is another constant, representing the molecular attraction between water molecules. The magnitude of the correction is about 2 gigapascals (20000 atmospheres).

The equation is stated in this form because the speed of sound in water is given by $\text{[math]}$ .

Thus water behaves as though it is an ideal gas that is already under about 20000 atmospheres (2 GPa) pressure, and explains why water is commonly assumed to be incompressible: when the external pressure changes from 1 atmosphere to 2 atmospheres (100 kPa to 200 kPa), the water behaves as an ideal gas would do when changing from 20001 to 20002 atmospheres (2000.1 MPa to 2000.2 MPa).

This equation mispredicts the specific heat capacity of water but few alternatives are available for severely nonisentropic processes such as strong shocks.

Ultrarelativistic equation of state

An ultrarelativistic fluid has equation of state

$\text{[math]}$

where $\text{[math]}$ is the pressure, $\text{[math]}$ is the energy density, and $\text{[math]}$ is the speed of sound.

Ideal Bose equation of state

The equation of state for an ideal Bose gas is

$\text{[math]}$

where α is an exponent specific to the system (e.g. in the absence of a potential field, α=3/2), z is exp(μ/kT) where μ is the chemical potential, Li is the polylogarithm, ζ is the Riemann zeta function, and T_c is the critical temperature at which a Bose-Einstein condensate begins to form.

Equations of state for solids

Johnson Holmquist Equation of State

Bibliography

Elliot & Lira, (1999). Introductory Chemical Engineering Thermodynamics, Prentice Hall.

References

1. ^ Peng, DY, and Robinson, DB. A New Two-Constant Equation of State. Industrial and Engineering Chemistry: Fundamentals. Vol. 15 (1976) pp. 59-64.

• • [ e] States of Matter (list)
Solid • Liquid • Gas • Plasma • Supercritical fluid • Superfluid • Supersolid • Degenerate matter • Quark-gluon plasma • Fermionic condensate • Bose–Einstein condensate • Strange matter • Melting point • Boiling point • Triple point • Critical point • Equation of state • Cooling curve

In cosmology, the equation of state of a perfect fluid is characterized by a dimensionless number w, equal to the ratio of its pressure p to its energy density ρ: . It is closely related to the thermodynamic equation of state and ideal gas law.
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Physics is the science of matter^[1] and its motion^[2]^[3], as well as space and time^[4]^[5] —the science that deals with concepts such as force, energy, mass, and charge.
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Thermodynamics (from the Greek θερμη, therme, meaning "heat" and δυναμις, dynamis, meaning "power") is a branch of physics that studies the effects of changes in temperature, pressure, and volume on
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A state variable is any variable which represents the state of an object.

Thermodynamic variables are sometimes called state variables.

Control Systems Engineering

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equations relating the various thermodynamic quantities. In chemical thermodynamics, which is a sub-branch of thermodynamics, for example, there are millions of useful equations.
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In structural analysis, constitutive relations connect applied stresses or forces to strains or deformations. The constitutive relations for linear materials are linear, and termed Hooke's law.
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In thermodynamics, a state function, or state quantity, is a property of a system that depends only on the current state of the system, not on the way in which the system got to that state. A state function describes the equilibrium state of a system.
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trillion fold).]]

Temperature is a physical property of a system that underlies the common notions of hot and cold; something that is hotter generally has the greater temperature. Temperature is one of the principal parameters of thermodynamics.
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Pressure (symbol: p) is the force per unit area applied on a surface in a direction perpendicular to that surface.

Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.
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The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. One-dimensional figures (such as lines) and two-dimensional shapes (such as squares) are assigned zero volume in the three-dimensional space.
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In thermodynamics, the internal energy of a thermodynamic system, or a body with well-defined boundaries, denoted by U, or sometimes E, is the total of the kinetic energy due to the motion of molecules (translational, rotational, vibrational) and
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FLUID (Fast Light User Interface Designer) is a graphical editor that is used to produce FLTK source code. FLUID edits and saves its state in text .fl files, which can be edited in a text editor for finer control over display and behavior.
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A solid object is in the states of matter characterized by resistance to deformation and changes of volume. At the microscopic scale, a solid has these properties :

The atoms or molecules that comprise the solid are packed closely together.

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STAR is an acronym for:

Organizations:

Society for Telescopy, Astronomy, and Radio, a non-profit astronomy club in New Jersey
Special Tasks and Rescue or Special Tactics and Response, synonyms for SWAT

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The ideal gas law is the equation of state of a hypothetical ideal gas, first stated by Benoît Paul Émile Clapeyron in 1834.

The state of an amount of gas is determined by its pressure, volume, and temperature according to the equation:

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A solid object is in the states of matter characterized by resistance to deformation and changes of volume. At the microscopic scale, a solid has these properties :

The atoms or molecules that comprise the solid are packed closely together.

..... Click the link for more information.

STAR is an acronym for:

Organizations:

Society for Telescopy, Astronomy, and Radio, a non-profit astronomy club in New Jersey
Special Tasks and Rescue or Special Tactics and Response, synonyms for SWAT

..... Click the link for more information.

129: 312.
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perfect fluid is a fluid that can be completely characterized by its rest frame energy density ρ and isotropic pressure p.

Real fluids are "sticky" and contain (and conduct) heat.
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Robert Boyle

Robert Boyle
Born 25 January 1627
Lismore Castle, Munster, Ireland
Died 30 December 1691 (aged 64)

Nationality Irish
Field Chemistry, Physics
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2, 1
(mildly basic oxide)
Electronegativity 2.00 (scale Pauling)
Ionization energies 1st: 1007.1 kJ/mol
2nd: 1810 kJ/mol
3rd: 3300 kJ/mol
Atomic radius 150 pm
Atomic radius (calc.
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Edme Mariotte (c. 1620 - May 12, 1684) was a French physicist and priest.^[1]

Mariotte is best known for his recognition in 1676 of Boyle's Law about the inverse relationship of volume and pressures in gases. In 1660 he had discovered the eye's blind spot.
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8th century - 9th century - 10th century
850s 860s 870s - 880s - 890s 900s 910s
885 886 887 - 888 - 889 890 891

:
Subjects: Archaeology - Architecture -
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Jacques Alexandre César Charles (November 12, 1746 – April 7, 1823) was a French inventor, scientist, mathematician, and balloonist.

Charles was born in Beaugency-sur-Loire, and made the first flight of a hydrogen balloon on August 271783.
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Joseph Louis Gay-Lussac (December 6, 1778 – May 9, 1850) was a French chemist and physicist. He is known mostly for two laws related to gases, and for his work on alcohol-water mixtures, which led to the degrees Gay-Lussac used to measure alcoholic beverages in many countries.
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Dalton's law (also called Dalton's law of partial pressures) states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture.
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Benoît Paul Émile Clapeyron (February 26, 1799 - January 28, 1864) was a French engineer and physicist, one of the founders of thermodynamics.

Life

Born in Paris, Clapeyron studied at the École polytechnique and the École des Mines, before leaving for Saint Petersburg in
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Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale
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Equation Of State

Information about Equation Of State

Overview

Historical

Boyle's law (1662)

Charles's law or Law of Charles and Gay-Lussac (1787)

Dalton's law of partial pressures (1801)

The ideal gas law (1834)

van der Waals equation of state

Major Equations of State

Classical ideal gas law

Cubic Equations of State

van der Waals equation of state

Redlich-Kwong equation of state

Soave modification of Redlich-Kwong

Peng-Robinson equation of state

Elliott, Suresh, Donohue equation of state

Non-cubic Equations of State

Dieterici equation of state

Virial Equations of State

Virial equation of state

The BWRS equation of state

Other Equations of State of Interest

Stiffened equation of state

Ultrarelativistic equation of state

Ideal Bose equation of state

Equations of state for solids

See also

Bibliography

References

Control Systems Engineering

Life